Compounds of formula (I) are disclosed in WO 02/50043, WO 2004/074263 and WO 2005/037824 as dual inhibitors of erbb1 receptor (EGFR) and erbB2 (Her2/neu) receptor tyrosine kinases, suitable for the treatment of e.g. benign or malignant tumours, particularly tumours of epithelial and neuroepithelial origin, metastasisation and the abnormal proliferation of vascular endothelial cells (neoangiogenesis), for treating diseases of the airways and lungs which are accompanied by increased or altered production of mucus caused by stimulation by tyrosine kinases, as well as for treating diseases of the gastrointestinal tract and bile duct and gall bladder which are associated with disrupted activity of the tyrosine kinases. The disclosure of WO 02/50043, WO 2004/074263 and WO 2005/037824 includes preparation as well as pharmaceutical formulations of the compounds and is incorporated by reference regarding these aspects. Furthermore, it is known for treatment of tumour diseases that the compounds may be used in monotherapy or in conjunction with other anti-tumour therapeutic agents, for example in combination with topoisomerase inhibitors (e.g. etoposide), mitosis inhibitors (e.g. vinblastine), compounds which interact with nucleic acids (e.g. cisplatin, cyclophosphamide, adriamycin), hormone antagonists (e.g. tamoxifen), inhibitors of metabolic processes (e.g. 5-FU etc.), cytokines (e.g. interferons) or antibodies.